1. Field of the Invention
This invention is concerned with a multifunctional fuel additive which is useful when employed in a liquid hydrocarbon fuel for an internal combustion engine. Owing to its reduced imide content, the additive does not degrade the water separation properties of the fuel.
2. Description of the Prior Art
The most pertinent art relating to this invention is coassigned U.S. Pat. No. 4,207,079, issued June 10, 1980. Said patent discloses and claims primary aliphatic hydrocarbon asparagine compounds possessing a high level of corrosion inhibition and carburetor detegency properties. The disclosure of said patent is incorporated herein by reference.
In the process disclosed in said patent, approximately two moles of a N-primary alkylalkylene diamine are reacted with a mole of maleic anhydride at a temperature ranging from about room temperature up to about 110.degree. C. maximum, preferably from about 60.degree. to 100.degree. C. The reaction preferably is carried out in a mineral reaction diluent and the products are then blended, without separation or purification, with about a 33 weight percent excess of the diamine thereby forming an additive containing about 33 weight percent asparagine as the active ingredient, about 33 weight percent of diamine and about 34 weight percent of mineral oil. In the process used for preparing the asparagine there are also results from 5 to 10 percent by weight of by-product succinimides which are not separated therefrom to minimize production costs. The present invention constitute an improvement over that of the above-mentioned patent and is based on the unexpected discovery that preparing the asparagine compound in the presence of excess diamine reduces the succinimide content and improves the water separation characteristics of the additive.